ZX80 and ZXCCB

[beanz]

I had a couple ZXCCB composite boards I'd purchased a while back and installed 1 in a zx81 and the other in a zx80 this weekend.

No problems with the one in the ZX81, but on the ZX80 there is no output at all no matter how much the trim pots are played with. The Docs on the ZXCCB (at least the ones I found) are not very good but I did have a diagram (again from a while back) that showed how to hook up the ZXCCB on the ZX80...as there are only two inputs, video and 5v to the modulator anyway wasn't a particularly difficult thing.

Anyway, no dice on the ZX80 unless I have a bad ZXCCB...The ZX80 was working on RF before installation and I can measure voltage on it so it's still working.

I have a few dead TS1000s (ZX81), would I be right in assuming I can take a modulator off one of those and put it on the ZX80 to get it up and running in RF again? (I removed the innards of the ZX80 modulator to put the ZXCCB in it).

[Fwapp]

It should work. I connected it in my ZX80 so that the voltages to the ZXCCB are taken directly from the regulator OP and the input to the zxccb is take from the video in to the modulator. I had first disconnected the modulator.

[1024MAK]

I haven't checked, but I would have thought they would be the same.

In any case, the type of modulator used only has three "inputs". Ground/0V, +5V DC supply and the video input. That's the same in a ZX80, ZX81 or even a Sinclair made ZX Spectrum.

Mark

[beanz]

Hmm maybe I have a bad ZXCCB board then, It's getting voltage as I measured it. I installed 2 ZXCCB boards in TS1000s with no problems at all and so felt confident to do it to my ZX80...having taken out the modulator innards to put the CCB board in.

Maybe I need to get another ZXCCB to try...are they still available? I can't find any links/contact info to get more.

[Moggy]

Hmm maybe I have a bad ZXCCB board then, It's getting voltage as I measured it. I installed 2 ZXCCB boards in TS1000s with no problems at all and so felt confident to do it to my ZX80...having taken out the modulator innards to put the CCB board in.

Maybe I need to get another ZXCCB to try...are they still available? I can't find any links/contact info to get more.

Works ok on my ZX80 too.

I was going to suggest that it might not work on a USA ZX80 but as it works on what I presume are genuine USA TS1000s as opposed to UK zeddies, then that sort of knocks that theory on the head.


A PM to pokemon perhaps for a definitive answer?

[beanz]

Thanks, yeah I sent him a PM. I was wondering the same (using it on a US ZX80 but deduced as you did if it works on a TS1000 it should work on a US ZX80)

[Moggy]

Thanks, yeah I sent him a PM. I was wondering the same (using it on a US ZX80 but deduced as you did if it works on a TS1000 it should work on a US ZX80)

The only defining difference is the lack of a ULA on the 80 but as the 80's circuitry is churning out a composite signal like the 81's ULA then the logical conclusion is a stuffed video jobby.

Just a thought you remembered to ground the black wire adequately?

Please let us know the outcome beanz.

[beanz]

I grounded the black the same as on the TS1000...both blacks soldered to the inside of the body of the modulator box and then a continuity test from the modulator box to other ground point on the board...all good.

And yep I'll let you know...I'm thinking I'll need to get another board though and it looks like Pokemon is out of stock for now (based on I don't see any on sale anywhere...still waiting to hear back from him). I might hookup a modulator off a couple of scrap TS1000s I have this weekend just to check it is still functional on RF and I didn't fry something during the installation...I hope it's just the ZXCCB board.

[Moggy]

I grounded the black the same as on the TS1000...both blacks soldered to the inside of the body of the modulator box and then a continuity test from the modulator box to other ground point on the board...all good.

Another daft thought, yellow and orange correct way round?

If so I'm stumped at this point.

[beanz]

Yes, checked those are right as the one I put in the TS1000 was actually reversed on the board (the red and orange)...so I double checked when I got the the ZX80 one that it wasn't the case on that one. Thanks for all the suggestions...I'm pretty much at the point of either it's the CCB board or something on the ZX80 didn't like me manhandling it. I REALLY hope it's just the CCB board. I'm kicking myself for taking out the modulator innards before testing the CCB board but It's such an easy install I was confident in what I was doing.